In laparoscopic surgical procedures, a small incision is made in the body and an elongate shaft of a surgical device is inserted through the incision to position a distal end of the shaft at a surgical site. In endoscopic procedures, the elongate shaft of a surgical device is inserted through a natural orifice, such as the mouth, vagina, or anus, and is advanced along a pathway to position a distal end of the device at a surgical site. Endoscopic procedures typically require the use of a flexible shaft to accommodate the tortuous pathway of the body lumen, whereas rigid shafts can be used in laparoscopic procedures. These tools can be used to engage and/or treat tissue in a number of ways to achieve a diagnostic or therapeutic effect.
Many current laparoscopic and endoscopic devices utilize articulating effectors to provide the user with more control over the orientation of the working end of the instrument. Integration of the controls for articulating, as well as actuating, a working end of a laparoscopic or endoscopic device tends to be complicated by the size constraints of the relatively small pathway through which it is inserted. The controls for an endoscopic device are further complicated by the flexibility of the shaft. Generally, the control motions are all transferred through the shaft as longitudinal translations, which can interfere with the flexibility of the shaft. Also, the control motion to actuate one aspect of the device may inadvertently cause actuation of a second aspect of the device. For instance, the application of force to actuate (i.e., fire, open and close, energize, etc.) the end effector might also cause undesirable articulation or “hinging” of the end effector. There is also a desire to lower the force necessary to articulate and/or actuate the working end to a level that all or a great majority of surgeons can handle. One known solution to lower the force-to-fire is to use electrical motors. However, surgeons typically prefer to experience feedback from the working end to assure proper operation of the end effector. The user-feedback effects are not suitably realizable in present motor-driven devices.
Accordingly, there remains a need for improved methods and devices for controlling movement of a working end of a surgical device.